Currently, as a maintenance management function in a communication network system such as Ethernet ®, OAM (Operation Administration Management) is proposed, and its standardization is advanced by ITU-T Recommendation Y.1731 and the like. For example, a communication node and the like can monitor a particular communication segment by transmitting and receiving an OAM-dedicated message.
In addition, Ethernet ®, IEEE 802.1ah, and IEEE 802.Qay, and the like also disclose a technology called PBB (Provider Backbone Bridge). For example, the PBB is a technology for capsulating a user MAC (Media Access Control) frame of a customer (user) network in a provider MAC frame of a provider (carrier) network (hereinafter, which will be referred to as PBB frame). The PBB can realize an extension of a VLAN ID.
FIGS. 21A-D show a format example of the PBB frame containing the customer MAC frame.
As illustrated in FIG. 21B, the PBB frame capsulates the customer MAC frame in a new MAC frame. For example, “B-MAC DA” and “B-MAC SA” are MAC addresses used in the PBB network, and “B-TAG” is a VLAN tag used in the PBB network. Also, “I-TAG” is a VLAN tag used in an edge node of the PBB network. Then, whereas a VLAN-ID in the “B-TAG” has 12 bits, a VLAN-ID in the “I-TAG” has 24 bits, and the VLAN-ID is extended.
FIG. 22 shows a format example of the PBB frame containing CCM (Continuous Check Message) of S-OAM (Service-OAM) (hereinafter, which will be referred to as S-OAM frame). For example, the S-OAM frame is used between the edge nodes of the PBB network, and while the edge node periodically transmits and receives the S-OAM frame, a reception interruption or the like in a particular communication segment in the PBB network is detected.
Japanese Laid-open Patent Publication No. 2008-167331 discloses the following technology.
For example, a first layer2-network apparatus further adds an OuterOAM header to an Ethernet OAM frame that should be transmitted to a second layer2-network apparatus via the network for transmission. Then, the second layer2-network apparatus removes the OuterOAM frame from the OAM frame received from the first layer2-network apparatus for transmission.